Why not look at how Simraceway built the physics for the R18? The Simraceway R18 was setup by Allan McNish, I doubt your get closer than that.
I just drove this, finally a decent Prototype for rfactor 2, raced against the EnduranceRacingX cars had a great time. Can't wait 'till Ales releases his. Oh and I loved the BES for rfactor 1 but they are way outdated for rfactor 2.
Sorry for the of topic but, to be honest, the bes mod is not so bad. And yes,i know what im talking of. ...as said, sorry.